<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    #result{
      width: 200px;
      height: 100px;
      border: 1px solid
    }
  </style>
  <title>Document</title>
</head>
<body>
  <div id="result"></div>
  <script>
    const result = document.getElementById('result')
    result.addEventListener('mouseover',function(){
      //1.创建对象
      const xhr = new XMLHttpRequest()
      //2.初始化  设置类型与url
      xhr.open('POST','http://127.0.0.1:8000/server')
      //设置请求头
      xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')
      xhr.setRequestHeader('name','jiqirui')
      //3.发送
      // xhr.send()
      xhr.send('a=100&b=200&c=300')//post请求体中设置参数
      //4.事件绑定
      xhr.onreadystatechange = function(){
        //判断
        if(xhr.readyState===4){
          if(xhr.status>=200&& xhr.status<300){
            //处理服务器端返回的结果
            result.innerHTML = xhr.response
          }
        }
      }
    })

  </script>
</body>
</html>